Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/06—Polyethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/08—Copolymers of ethene
  • C08L23/0807—Copolymers of ethene with unsaturated hydrocarbons only containing four or more carbon atoms
  • C08L23/0815—Copolymers of ethene with unsaturated hydrocarbons only containing four or more carbon atoms with aliphatic 1-olefins containing one carbon-to-carbon double bond
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
  • H01B3/44—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L25/00—Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
  • C08L25/02—Homopolymers or copolymers of hydrocarbons
  • C08L25/04—Homopolymers or copolymers of styrene
  • C08L25/08—Copolymers of styrene
  • C08L25/12—Copolymers of styrene with unsaturated nitriles
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L51/06—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L53/00—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L53/02—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers of vinyl-aromatic monomers and conjugated dienes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers

Definitions

• the present invention relates to a synthetic material of electrical insulation for high voltage power cable, in particular but not exclusively in direct current.
• the transport of energy by direct current cables has several advantages (high power and low electrical losses) compared to the transport by alternating current cables, when the distances reach or exceed 50 km.
• the cables currently used for direct current are isolated with paper impregnated with fluid or viscous oil. This technology is reliable but cumbersome, both because of the manufacturing and installation conditions and of operation (weight, periodic maintenance, etc ).
• Synthetic insulating materials widely used for AC cables, are attractive in terms of installation, operation and maintenance and justify studies undertaken for twenty-five years.
• the main macromolecular materials used in high-voltage alternative cables are crosslinked or non-crosslinked polyethylenes and EPR type rubbers.
• Today no cable with extruded synthetic insulation is marketed for high voltage direct current. Indeed, continuous high voltage induces permanent space charges which change over time. This development can locally cause significant increases in electric field and lead to breakdowns.
• the object of the present invention is to produce a synthetic insulating material, extrudable, which has good mechanical properties, which is stable over time, and which has dielectric qualities at cable operating temperatures, better than those of known materials. .
• Said copolymer can be a diblock block copolymer with gradual transition or not or triblock, a first block of which is made up of monomer units identical to those of said first polymer, and a second block of which is made up of monomer units identical to those of said second polymer .
• Said copolymer can also be obtained by chemical grafting reaction of molecules of said first / or said second polymer, on a macromolecular chain compatible with said second / or said first polymer.
• This grafting can also be carried out when the various constituents are mixed.
• Said second polymer which normally constitutes a separate phase when it is mixed with said first polymer is chosen to be fusible, or soluble in a solvent for the first polymer, so that it can be mixed with this first polymer and said copolymer.
• the manufacture of said alloy is carried out at a temperature such that all of the constituents are viscous.
• the latter must be thermally stable at the temperatures used for the preparation of the alloy or for its extrusion.
• said first polymer is a low density polyethylene, or a linear low density polyethylene
• said second polymer is a high density polyethylene
• said copolymer is a copolymer of polyethylene and EPDM.
• said first polymer is a low density polyethylene, or a linear low density polyethylene, or a high density polyethylene
• said second polymer is a polystyrene and said copolymer is chosen from a triblock block copolymer or diblock, with or without gradual transition, of hydrogenated polybutadiene and polystyrene, and a grafted copolymer of hydrogenated polybutadiene and polystyrene.
• said first polymer is a polyethylene
• said second polymer is polypropylene
• said copolymer is EPDM
• said first polymer is a polyethylene
• said second polymer is a polyamide
• said copolymer is chosen from a partially hydrolyzed polyethylene-polymethyl methacrylate copolymer, a block copolymer of hydrogenated polybutadiene and of polycaprolactam, and a copolymer composed of a polyolefin grafted with maleic anhydride.
• said first polymer is a polyethylene
• said second polymer a polyester
• said copolymer is a block or graft copolymer of hydrogenated polybutadiene and of polyester.
• said first polymer is a polyethylene
• said second polymer a polycarbonate and said copolymer a graft copolymer of polyethylene and polycarbonate.
• the polymer alloy according to the invention can be crosslinked or not. It is extrudable.
• the compatibilizing copolymer makes it possible to avoid the nuisance breakdown phenomena usually observed in extrudable synthetic insulation materials, when it is attempted to use them to produce cables for transporting direct current under high voltage.
• the quantity of electric charges in the alloy is less than that which is induced in each of the materials.
• the depolarization current measured at the moment when the electric field is canceled, characterizes the quantity of the charges induced. This depolarization current has been found to be lower and more quickly zero in the alloys according to the invention than in each of its constituent polymers taken in isolation.
• Six materials are produced comprising as first polymer polyethylene and as second polymer polystyrene.
• LDPE low density polyethylene
• LLDPE linear low density polyethylene
• HDPE high density polyethylene
• the materials according to the invention numbered 2, 4 and 6 in Table I further comprise a block copolymer of hydrogenated polybutadiene and polystyrene, such as for example the copolymer sold under the brand "KRATON" by the company SHELL.
• Table I mentions the percentages by weight of the various constituents of each material as well as the values of the breaking stress ⁇ ⁇ (in MPa) and the elongation at break ⁇ ⁇ (%) at a temperature equal to 25 ° C. .
• Eight materials were produced comprising polyethylene 6 as the first polymer and polyamide 6 as the second polymer.
• the materials numbered 7, 9, 11 and 13 in Table II are mixtures of these two polymers which are incompatible, and do not form part of the invention.
• the materials according to the invention numbered 8, 10, 12 and 14 in Table II further comprise a copolymer of hydrogenated polybutadiene and polycaprolactam, or a copolymer composed of a polyolefin grafted with maleic anhydride, such as for example " EXXELOR VA 1801 "sold by the EXXON Company.
• Table II lists the percentages by weight of the various constituents of each material as well as the values of the breaking stress ⁇ ⁇ (in MPa) and the elongation at break ⁇ ⁇ (%) at a temperature equal to 25 ° C. .
• the depolarization currents are then studied in a pure low density polyethylene (LDPE) sample and the values are compared to those obtained under the same conditions with samples of the mixture 7 and of the alloys 2 and 8 according to the invention.
• LDPE low density polyethylene
• the method consists in polarizing the sample by applying a high DC voltage, then in depolarizing it by measuring the current resulting from this depolarization as a function of the relaxation time.
• the temperature is 70 ° C. (the migration of space charges is faster at high temperature).
• the bias voltage is 10,000 volts.
• Each sample is a disc 80 mm in diameter and 1 mm thick. Its surface is flat and smooth and thoroughly cleaned before measurement.
• the polarization is maintained for 72 hours and the depolarization lasts for approximately 10 minutes.
• Table III mentions the values k1 and k2 with: (the material being the mixture or the alloy tested) This table makes it possible to evaluate the performances of the alloys according to the invention compared to pure low density polyethylene (the dielectric properties of the materials are all the better the higher the k1 and k2 ratios).
• the material according to the invention can also be advantageously used in alternating current.
• Breakdown tests with alternating current at room temperature were carried out according to the procedure described in international standard IEC 243-1 relating to electrical tests on solid dielectrics.
• the breakdown rate was 2000V / sec.
• the parameter b is an estimator of the dispersion of the breakdown gradients. The greater the dispersion, the larger the b.
• Table IV shows the advantage of using an alloy according to the invention rather than the PRC. TABLE IV Type of material b Alloy # 2 15 PRC 12
• the increase in parameter b makes it possible to increase the lifetime of the insulation material for the same operating electric field gradient.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Organic Insulating Materials (AREA)

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Citations (5)

• 1992
  • 1992-05-12 CA CA 2068467 patent/CA2068467A1/fr not_active Abandoned
  • 1992-05-12 EP EP92107975A patent/EP0513731A1/de not_active Withdrawn
  • 1992-05-13 JP JP4120599A patent/JPH06203637A/ja active Pending

Patent Citations (5)

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